Process of producing colloidal metal hydroxides



Patented July 15, 1941 'ATENT OFFICE PROCESS PRODUCING COLLOIDAL METAL HYDRQXIDES Rudolph s. ma Milligan College, Tenn.

No Drawing.

Application April 17, 1939,

Serial No. 268,384

8 Claims.

The present invention relates to a process of preparing pure colloidal metal hydroxides especially for therapeutic purposes.

One object of my invention has to do with the controlled decomposition of metal alkyls in the presence of an inert diluent.

Another object of my invention relates to the decomposition of metal alkyls in water while being diluted with an inert gas.

A third object of my invention has to do with a novel synthesis of metal alkyls, especially aluminum triethyl, per se by causing a finely divided metal to react upon diethyl mercury at relatively low temperatures.

A fourth object of this invention relates to the production of metal hydroxide suspensions containing a definite amount of hydroxide particles.

Other objects of my invention will become apparent to those skilled in the art after a study of the following specification.

Colloidal metal hydroxides have, heretofore, been prepared by interaction of water-soluble electrolytes. In this manner, colloidal aluminum hydroxide, for example, may be formed by causing sodium hydroxide to react upon aluminum 2 sulphate. However, it becomes almost impossible to thoroughly remove the sodium sulphate adsorbed to the gelatinous aluminum hydroxide, even by prolonged dialysis. These impurities are,

however, often detrimental when colloidal hydroxides' are used in therapeutics for injections, etc.

Until the present time, it has been practically impossible to form colloidal metal hydroxides from corresponding metal alkyls for the reason that these alkyls ignite and explode in the presence of minute quantities of water. When aluminum triethyl, for example, is introduced into water, colloidal aluminum hydroxide is formed in accordance with the following equation:

' A1(C21H5) 2 plus 3(H2O) Z A1(OH)3 plus 3(C2Hc) reaction is sufficiently retarded to avoid ignition and explosion of the metal alkyl. The inert liquid may be removed from the hydrosol by evaporation, etc. Instead of diluting the metal alkyl with an inert liquid, it may be diluted with an inert gas, such as nitrogen, helium, krypton, neon, xenon, carbon dioxide, etc., these gases being substantially recovered after the reaction ha taken place between the metal alkyl and water. It is to be noted, that any metal alleyl can be used in my process which decomposes in water to form a substantially water-insoluble hydroxide, such as beryllium dialkyls, aluminum trialkyls, gallium trialkyls, magnesium dialkyls, zinc diallcyls, cadmium alkyls, bismuth trialkyls, etc. In other words, I may use any metal alkyl having the structure: (CnHZn+l)-T'M, in which 0: represents the valency of the metal used, provided that the metal alkyl decomposes in water and forms a substantially water-insoluble hydroxide therein.

The metal alkyls, used in the reaction, may be prepared as follows:

1. By the action of metals on alkyl iodides.

2. By the action of alloy on alkyl iodides.

3. By the action of metallo-organic bodies on metals.

4. By the action of metallic chlorides on metallic-organic derivatives (zinc alhyls, magnesium alkyl halides, etc.)

Aluminum triethyl, for example, may be formed by causing mercury diethyl to react upon finely divided aluminum in an autoclave at about 130 to 145 C. for several hours. The impure aluminum triethyl is then distilled in the complete absence of water in a column filled with carefully dried carbon dioxide. About 50 to 65% of the theoretically possible yield of aluminum triethyl is obtained in this manner, and it may be preserved for relatively long period of time over dry carbon dioxide. The mercury diethyl, employed in the reaction, may be formed by means of the Grignard reaction. Other metal allcyls, such as aluminum trimethyl, beryllium trimethyl, beryllium triethyl, gallium trimethyl, gallium triethyl, zinc dimethyl, zinc diethyl, cadmium methyl, cadmium ethyl, antimony trimethyl, antimony triethyl, etc., may be produced in accordance with the method set forth above.

When a metal alkyl is slowly introduced into distilled water in the presence of an inert, gaseous or liquid diluent, the corresponding metal hydroxide is formed therein in finely divided form. By regulating the amount of diluted alkyl introduced into a given amount of water, more or less 55 concentrated hydrosols may be obtained. These hydrosols, free from electrolytes, will settle their solid phase on standing, and it becomes necessary to float the particles by means of protective colloids, such as glues, gelatine, etc. It is also possible to determine first the electric charge of the hydroxide particles and then to peptize the same by addition of minute amounts of electrolytes. Aluminum hydroxide particles, for example, have a positive charge, and thus then can be peptized by minute acid additions. Electro-positive particles must be peptized with acids and electronegative ones with alkalies.

Example 1 About 50 grams of mercury diethyl are heated for several hours in an autoclave with about grams of finely divided aluminum (or another metal) at a temperature of about 130 to 145 C. The impure aluminum triethyl is subsequently purified by distillation over dry carbon dioxide and collected in complete absence of water in a dry flask. Dry nitrogen, for example, is then passed through the flask which is warmed to about 100 C. into distilled water. Although the heating of the alkyl-containing flask facilitates an intimate mixing of the alkyl with nitrogen, excessive heating thereof should be avoided. The aluminum hydroxide formed in the water may be stabilized as set forth above. It must be emphasized that all devices and chemicals used have to be completely dry to avoid explosions.

Example 2 A metal alkyl, such as aluminum triethyl, etc., is dissolved in an inert liquid, for example, an alcohol, ether, ketone, etc., and the mixture slowly introduced into distilled Water to form a colloidal hydroxide. The inert liquids must be completely dehydrated before admixing them with the metal alkyl. The inert liquid, i. e., diluent, need not be a true solvent for the metal alkyl. The alkyl may be also homogenized in the diluent. The distilled water into which the alkyl-diluent mixture is introduced is preferably cooled to retard the reaction. Standardized suspensions may be prepared by adding a fixed amount of alkyl to a predetermined amount of water. The hydroxide hydrosol may, subsequently, be stabilized in accordance with methods set forth in Example 1.

After having described my invention, I- wish to emphasize that in the appended claims the term metal alkyl covers only such alkyls which are decomposed by water to form water-insoluble or substantially water-insoluble metal hydroxides. The term inert diluent used in the claims covers only such organic liquids which either dissolve or suspend metal alkyls and which do not interfere with the reaction, i. e., remain unattacked by the metal alkyl in the Water and are removable from the same, and furthermore, it covers inert gases as set forth in the specification. It is not intended to cover solid substances serving as diluents, because they have been found inoperative.

Modifications may be made of my invention by those skilled in the art without departing from its spirit and scope, and I desire to cover all of these modifications as defined by the appended claims. In these claims the term reactive metal" is intended to cover metals capable of interacting with metal alkyls, such as sodium, potassium, zinc, aluminum, magnesium, etc. The term relatively inert metal alkyl embraces alkyls of relatively inert metals such as mercury, lead, vanadium, copper, etc., the metals of these alkyls being capable of replacement by the reactive metals used in the reaction.

The present application is a continuation in part of my co-pending application, now Patent Number 2,154,603; filed August 15, 1935.

I claim:

1. The process of producing a colloidal metal hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of an anhydrous inert gas and a metal alkyl and reacting the mixture with water to form a metal hydroxide in colloidal form.

2. The process of producing a colloidal metal hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of an anhydrous inert gas and a metal alkyl and reacting the mixture with water to form a metal hydroxide in colloidal form and stabilizing the so formed hydrosol.

3. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of an anhydrous inert gas and aluminum alkyl and reacting said mixture with water to form colloidal aluminum hydroxide.

4. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of anhydrous nitrogen and aluminum alkyl and reacting the mixture with water to form colloidal aluminum hydroxide.

5. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of an anhydrous inert gas and aluminum triethyl and reacting said mixture with water to form colloidal aluminum hydroxide.

6. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of an anhydrous inert gas and aluminum triethyl and reacting the mixture with water to form aluminum hydroxide in colloidal form and stabilizing the so formed hydrosol.

7. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of anhydrous nitrogen and aluminum triethyl and reacting said mixture with water to form colloidal aluminum hydroxide.

8. The process of producing a colloidal aluminum hydroxide free from contaminating electrolytes which comprises forming an intimate mixture of anhydrous nitrogen and aluminum triethyl and reacting the mixture with water to form aluminum hydroxide in colloidal form and stabilizing the so formed hydrosol.

RUDOLPH S. BLEY. 

